Covered rollers have been used as mill rolls for decades in primary metal fabrication operations. They are broken down in to two groups. The first group of covered rollers as mill rolls is shafts covered with a rubber, urethane, or vinyl covering. These rollers are particularly useful where expense is an issue and performance in fluid environments, particularly acidic or caustic, is not required. Included in this group, for example, are covered rollers used as brindle rolls, table rolls, deflecting rolls, and steering rolls.
The second group of covered rollers as mill rolls is covered with non-woven material. These covered rollers are much more expensive than rubber, urethane, or vinyl covered rollers but, typically, have a significantly longer life, higher coefficient of friction, and better fluid wringing properties than their rubber, urethane, or vinyl covered shaft counterparts. These covered rollers are particularly useful in situations where they are exposed to oils or acidic or caustic conditions. Included in this group, for example, are covered rollers used as snubber rolls, pinch rolls, de-oiler rolls, cleaning rolls, wringer rolls—both oil applications and chemical solution application, and oiler rolls.
The current use of non-woven covered rollers is dictated by cost and performance. Typically, the non-woven covered rollers are made by first coating a non-woven web with a resin and curing the resin, stamping out hollow disks, stacking and compressing the disks into a hollow cylinder, and retaining the cylinder to a metal shaft with retention plates and keys. These large number of steps result in covered rollers that are much more expensive than rubber, urethane, or vinyl covered rollers. However, because non-woven webs on a non-woven covered rollers have a void volume, their surfaces are able to remove small metal debris from metal webs during metal fabrication processes and temporarily compress when exposed to larger debris without tearing or cutting as occurs with rubber, urethane, or vinyl covered rollers. Non-woven covered rollers are typically used in situations where the larger number of steps resulting in significantly higher costs over those of the first group are worth one or more of longer life, higher surface friction, harder surfaces, and the presence of void volume that provide self-cleaning characteristics, greater damage resistance, and excess fluid removal capability.